Hydraulic machines, for example, hydraulic excavators, use engines to drive hydraulic pumps, which in turn provide hydraulic power to a plurality of hydraulic circuits of the hydraulic machines. Each hydraulic circuit may include one or more actuators, for example, hydraulic cylinders and/or hydraulic motors. The plurality of hydraulic actuators each may require a flow of hydraulic fluid from one or more hydraulic pumps to operate the associated hydraulic cylinders or hydraulic motors. The amount of flow required by each hydraulic actuator may vary depending on an operator input. The hydraulic pumps may be controlled to supply the hydraulic system with the hydraulic flow required by each of the plurality of hydraulic actuators.
In some systems, the plurality of hydraulic circuits include a closed loop hydraulic circuit. The closed loop hydraulic circuit may include one or more hydraulic motors supplied with the required flow by a plurality of variable displacement pumps fluidly connected in parallel in the closed loop hydraulic circuit. Various control systems have been implemented to control the plurality of variable displacement pumps in the closed loop hydraulic circuit.
The disclosed systems and methods are directed at least in part to improving known systems.